The invention relates to a turbine engine with a turbine engine fuel system, and more particularly to a turbine engine that includes a turbocompressor for supplying high pressure compressed atomizing fluid to the turbine engine fuel system.
High pressure air is commonly supplied to liquid fuel nozzles in gas turbine engine fuel systems to improve the atomization of the fuel droplets, help cool the fuel nozzles and also to provide purge capability to remove residual fuel and other liquid in the nozzles when switching from a liquid fuel to a natural gas fuel. It is necessary that such high pressure atomizing air be flowed to the fuel nozzles at pressures about 20% higher than the pressure of air that is typically supplied to a fuel system combustion chamber(e.g. 10-30 bars), and with a mass flow rate that may be up to three times that of the fuel mass flow rate.
In order to achieve the required pressure and mass flow rate requirements, conventional compression systems designed to boost atomizing air pressure typically use reciprocating compressors that are driven by an electric motor. The resulting atomizing systems are large and expensive and do not deliver high pressure atomizing air to the gas turbine engine fuel system at a steady flow rate. Because of the nature of such reciprocating or piston type compressors, the supplied pressurized atomizing air may include a pressure pulsation which produces a pressure increase or pulse in the supplied atomizing air, and these pulsations contribute to combustion instability in the gas turbine engine fuel system, and may also contribute to fretting in fuel system supply lines or conduits.
An additional problem with the conventional motor driven approach to providing atomizing air to gas turbine engine fuel systems is the circumstances surrounding a loss of utility power. In the event of a power failure, the motor driving the reciprocating compressor will stop and the flow of pressurized atomizing air to the gas turbine engine fuel system fuel system components such as the fuel nozzles is immediately interrupted causing the fuel nozzles to coke and clog. Since the power required to operate the compressor is on the order of 20 kW providing battery backup is impractical and adds cost and complexity to the atomizing air supply system.
The foregoing illustrates limitations known to exist in present devices and methods. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.